Oven installation for use in the manufacture of a plurality of enameled wires

ABSTRACT

An oven body contains first and second drying retorts. A plurality of wire-handling lines are provided, each of which is operable to move a wire to be enameled in a first direction along a first pass path through first enamel coating means and thereafter through said first drying retort in a first plane, then to move said wire in a second direction, which is opposite to the first, along a second pass path through second enamel coating means and thereafter through said second drying retort in a second plane, which is parallel to said first plane, and to repeat said movement of said wire in said first direction through said first enamel coating means and through said first retort in said first direction in said first plane along at least one additional odd-numbered pass path and through said second coating means and said second retort in said second direction in said second plane along at least one additional even-numbered pass path. Said first and second planes are common to all said wirehandling lines. Each of said wire-handling lines comprises first reversing means for guiding said wire from each odd-numbered pass path to the next succeeding even-numbered pass path, and second reversing means for guiding said wire from each but the last even-numbered pass path to the next succeeding odd-numbered pass path. Said first reversing means comprises first axle means extending in said first plane, a first set of loose pulleys freely rotatably mounted independently of each other on said first axle means, second axle means extending in said second plane, and a second set of pulleys freely rotatably mounted independently of each other on said second axle means. Said second reversing means of each of said wire-handling lines comprise a single multigrooved pulley. Each of said wire-handling lines comprises a variable-speed drive unit and an endless tensile element operatively connecting said drive unit to said multigrooved pulley to drive the same, whereby said multigrooved pulley is operable to pull said wire through said drying retorts. All said multigrooved pulleys are rotatably mounted on a common axle.

United States Patent [72] Inventor August Fuchs 76 Koerblergase, Graz,Austria [21] Appl. No. 882,124 [22] Filed Dec. 4, 1969 [4S] PatentedAug. 3, 1971 [32] Priority Dec. 18, 1968 [33] Austria [31 12335/68 [54]OVEN INSTALLATION FOR USE'IN THE MANUFACTURE OF A PLURALITY OF ENAMELEDWIRES 10 Claims, 3 Drawing Figs.

[52] U.S.Cl 118/65, 118/500, 226/91, 226/110, 242/4703 51 Int.ClBOScll/12 [50] Field of Search lI8/DlG.

I9, DIG. 20, DIG. 21, DIG. 22, 64, 65, 419, 420; 226/91, 1 10; 34/120;242/4703 Primary Examiner-Morris Kaplan A1l0mey McGlew and TuttleABSTRACT: An oven body contains first and second drying retorts. Aplurality of wire-handling lines are provided, each of which is operableto move a wire to be enameled in a first direction along a first passpath through first enamel coating means and thereafter through saidfirst drying retort in a first plane, then to move said wire in a seconddirection, which is opposite to the first, along a second pass paththrough second enamel coating means and thereafter through said seconddrying retort in a second plane, which is parallel to said first plane,and to repeat said movement of said wire in said first direction throughsaid first enamel coating means and through said first retort in saidfirst direction in said first plane along at least one additionalodd-numbered pass path and through said second coating means and saidsecond retort in said second direction in said second plane along atleast one additional even-numbered pass path. Said first and secondplanes are common to all said wire-handling lines. Each of saidwire-handling lines comprises first reversing means for guiding saidwire from each odd-numbered pass path to the next succeedingeven-numbered pass path, and second reversing means for guiding saidwire from each but the last even-numbered pass path to the nextsucceeding odd-numbered pass path. Said first reversing means comprisesfirst axle means extending in said first plane, a first set of loosepulleys freely rotatably mounted independently of each other on saidfirst axle means, second axle means extending in said second plane, anda second set of pulleys freely rotatably mounted independently of eachother on said second axle means. Said second reversing means of each ofsaid wire-handling lines comprise a single multigrooved pulley. Each ofsaid wire-handling lines comprises a variable-speed drive unit and anendless tensile element operatively connecting said drive unit to saidmultigrooved pulley to drive the same, whereby said multigrooved pulleyis operable to pull said wire through said drying retorts. All saidmultigrooved pulleys are rotatably mounted on a common axle.

PATENTED AUG 31971 I N VENTOR fit 605T FUCI/S ATTORNEYS OVENINSTALLATION FOR USE [N THE MANUFACTURE OF A PLURALITY OF ENAMELED WIRESThis invention relates to an oven installation for use in themanufacture of a plurality of enameled wires, which installationcomprises drying retorts, through which each wire is moved several timesin mutually opposite directions in two parallel planes after individualenamel coating treatments and reversals until a coating having a desiredthickness has been formed. and the oven 15 provided on one side with aseparate, loose deflecting pulley for each pass of each wire, and on theother side with a single grooved pulley for each wire, which groovedpulleys are rotatably mounted on a common axle and by means of which thepull tending to move the wires through the drying retorts is maintained.

in a known oven installation for use in the manufacture of enameledwire, the oven is provided on that side which is opposite to the loosedeflecting pulley with a common grooved roll for all wires and said rollis driven by a variable transmission and the diameters of the groovesfor the successive reversals of each wire are so graded that a uniformtension is maintained and slip is avoided. Each wire 15 pulled through adrying retort after each reversal and the tension is minimized in eachwire portion between reversals and will not increase cumulativelythroughout the wire; the peripheral velocity of that common grooved rollcontrols the uniform speed of travel of all wires in the oveninstallation. After the last drying pass, the finished insulated wire iswound up on a takeup reel, which is driven with a forward slip by meansof a slip clutch so that the the takeup tension is adjustable ln thatoven installation, a broken wire cannot be pulled without interferencewith the remaining wires so that the production with respect to suchbroken wires will be interrupted until the entire oven installation hasbeen shut down. either because the production is no longer economicalas'several wires have broken or for other operational reasons.

In another oven installation for use in the manufacture of enameledwire, this disadvantage is avoided in that the grooved roll is dividedinto sections equal in number to the wires and these roll sections aredriven from a common shaft by clutches so that each wire can beindividually stopped and pulled independently of the others. As aresult, the loss of production due to breakage of individuahwires willbe relatively small. Because there is a limitation as regards the widthof the drying retort in view of the heat distribution along the same,the distances between the individual parallel wires must be minimized sothat the clutch members must be small too. This makes the control of theclutches very difficult and renders them liable to be deranged In thisoven installation too, all wires are driven at the same speed from thecommon shaft so that only wires equal in diameter can be treated at thesame time.

In order to avoid the difficulty mentioned last, an oven installation ofa different basic type has been developed for use in the manufacture ofenameled wire. In that plant, an oven body incorporates mutuallyindependent drying retorts in a number which corresponds to the numberof wires so that reversing rolls which control the withdrawal ofrespective wires can be mounted separately of each other and the meansfor driving each of said rolls can be conveniently accommodated. In thisarrangement the individual wires are entirely independent of each otheras regards the removal of any trouble as well as regards the speed atwhich the wires are withdrawn so that the diameter of each wire may befreely chosen. It is also possible to select any desired type of enamelfor each wire. On the other hand, the provision of numerous individualretorts and the accessories required for these retorts, such astemperature controllers, circulation fans, etc., involves thedisadvantages that a high capital investment is required, theinstallation is highly liable to be deranged, and the energy consumptionis considerable In an oven installation of the kind defined firsthereinbefore, which installation is intended for use in the manufactureof enameled wire and comprises a single oven body having one or moredrying retorts, all above-mentioned disadvantages of the various knownmultiple-line oven installations are avoided according to the inventionin a simple and reliable manner in that each of the grooved pulleyswhich are mounted on a common axle and around which a wire is trainedare mutually independently driven by a separate, variable-speed driveunit, preferably a variable-speed electric motor, through theintermediary of V-belts or the like. These adjustable drive units forthe grooved pulleys associated with the respective wires are preferablydisposed between the oven body, these grooved pulleys and the wirepasses moving in opposite directions and two axles each carrying a smallloose individual pulley for each wire pass are preferably arranged asuitable distance apart on the opposite outer reversing point.

In these multiple-line oven installations according to the mvention,each wire-handling line is entirely independent of the others as regardsthe selection of the diameters of the wires to be treated and the speedat which these wires move through the drying retorts as well as in thecase of any trouble Each of the wires moving one beside the otherthrough one and the same drying retort can be continuously controlled inspeed between standstill and a maximum so that the wire can be pulled orreadjusted or the wire-handling line may be altered without interferencewith the remaining production. just as in a single-line oven. The wirepass paths of each wire-handling line are closely spaced on the commongrooved pulley so that a relatively large number of closely spaced wirepass paths can be accommodated within a small space if an insulatingenamel coating having a predetermined total thickness is required. thisarrangement will result in the application of very thin individual coatsduring each pass so that under given operating conditions the wires canbe moved at a high speed through the drying retorts and the output aswell as the quality of the insulation can be increased. Anotherimportant advantage of the above-mentioned arrangement is the greatrange within which the width of the drying retort and with it the numberof wire-handling lines to be installed in an oven installation can beselected. Each independent wire-handling line providing for a largenumber of passes occupies only a fraction of the width of the retort sothat even with a highly unfavorable ration between the length and widthof the drying retort the temperature differences which may developacross the width of the retort will have no effect because the speed oftravel in each wire-handling line can be entirely independentlyselected.

In the takeup section of the oven installation for use in themanufacture of enameled wire, a single takeup reel may be provided foreach wire-handling line or two reels may be provided for each line andarranged for a semiautomatic or fully automatic replacement. In thelatter case, the full takeup reel is automatically replaced by an emptyone without an interruption of the travel of the wire. These takeupreels will be driven by means of slip clutches independently of themeans for driving the associated grooved pulleys.

In a preferred embodiment of this oven installation for use in themanufacture of enameled wire, the takeup reels provided in the takeupsection and associated each with a wirehandling line are driven each bya variable-tension motor, e.g., a so-called hyperbolic motor, the speedof which is automatically controlled in response to the speed of theassociated driven grooved pulley Hyperbolic motors are direct currentmotors having a hyperbolic operating characteristic (torquespeedcharacteristic In such arrangement in which the takeup of each finishedwire leaving the drying retort is automatically controlled independentlyof the other wires, the for ward slip of each reel and the speed atwhich its wire is withdrawn are controlled in a simple manner by apushbutton or the like and without a change of the adjustable tension ofthe wire, which remains constant regardless of the increasing diameterof the package.

In this oven installation for use in the manufacture of enameled wire,the driven grooved pulley of each wire-handling line IS suitably engagedat its last groove by a pressure roller, by means of which the movementof the wire coming from the drying retort is maintained regardless ofthe tension eterted by the takeup reel. Particularly where individualtakeup reels are used this arrangement will avoid an interruption of thetravel of the wire during a replacement of reels and any substantialtakeup tension will be kept from the wire in the drying retort. wherethe wire is hot and can be stretched more easily Besides. an automaticcontrol device may be provided for stopping each wire-handling lineduring an interruption of its normal operation, e.g.. when a wire hasbroken, so that the need for a continuous supervision is eliminated to alarge extent Finally, to provide a two-layer enamel coating, the oveninstallation according to the invention for use in the manufacture ofenameled wire may be designed so that four drying re torts may bearranged one over the other in a common oven body and together with theassociated guiding and reversing elements form two identicalmultiple-line enameling systems. In this case, a plurality of wires arefirst moved in opposite directions, e.g., in the two upper dryingretorts until an enamel primer coat in a desired thickness has beenobtained, and this wire having a single enamel coat is reversed to thesectional grooved roll of the other (lower) enameling system and ismoved through the two drying retorts of the latter, where the desiredenamel cover coat is applied.

An embodiment of an oven installation according to the invention for usein the manufacture of enameled wire is shown by way of example in thedrawing in which FIGS. 1 and 2 are, respectively. a side elevation and atop plan view showing the so-called basic unit of such oveninstallation, comprising two drying retorts which are accommodated in acommon oven body, and a total of eight lines for handling wires whichare moved through both retorts.

FIG 3 is an enlarged view showing the grooved pulley of onewire-handling line and the drive unit for such pulley.

The wires are supplied from eight supply reels 1, which have verticalaxes and from which each wire is guided by two superimposed sectionaldeflecting pulleys 2 and 2 along parallel horizontal paths into the oveninstallation disposed above the supply reels. Each wire D passes firstthrough the common annealing furnace 3, an adjustable snubber 4, whichsucceeds the furnace 3, an associated grooved pulley 15, the firstenamel coating vessel 11a and the uppertdrying retort 10a, which isdisposed in the oven body 10 and common to all wires, whereafter eachwire is reversed by being trained around two individual deflectingpulleys 13 and 13', which are associated with each pass and are freelyrotatably mounted and spaced suitable distances apart The wire movesthen in the opposite direction through the second enamel coating vessel11b and the lower drying retort 10b to the driven grooved pulley l andis trained around the same and thus reversed to move in a second pair ofpasses through both enamel coating vessels 11a, 11b and drying retortsa, 10 b etc. After a plurality of pairs of passes, the finished enamelwire D is withdrawn from the grooved pulley and supplied to the takeupstation 20.

Two vertically spaced axles l2 and 12' carry small loose individualpulleys 13, 13 for each pass of the wire at the outer reversing point(which is on the right in the drawing). Involving only a smallexpenditure. this arrangement ensures that a sufficiently large spacingwill be maintained between the upper and lower pass paths of each wireD. The grooved pulleys 15 are mounted on the common axle 14, which isdisposed on the left of the oven body 10. Each of the grooved pulleys 15is associated with one wire D and is driven from a separate,speed-variable electric motor 16 by a V-belt 16' or the like. Thesedrive units 16 will determine the speed of travel of the wire in theoven installation and are suitably arranged in the space between theoven body 10 and the grooved pulleys 15 between the upper and lower wirepasses so that the oven installation can be controlled withoutobstruction.

After each application of an enamel coat to a wire D in one of theenamel coating vessels Ila and 1111, the wire is reversed by one of thereversing systems 13-13 and 14-15 disposed on opposite sides of the ovenand is then moved through one of the two drying retorts 10a and 10b inthe oven body 10. The wire is moved through these two retorts inmutually opposite directions and in a number of passes until theinsulating enamel coating has the desired total thickness. The finishedenamel wire D which leaves the oven body 10 after the last pass is heldfrom below by means ofa pressure roller 17 at the last groove of thedriven grooved pulley 15; this is the last groove on the right in FIG.3. This arrangement ensures that during a replacement of the succeedingtakeup reels, when the takeup tension is eliminated, the driven groovedpulley 15 will maintain the continuous travel of the wire D. Eachfinished enameled wire D which is withdrawn from the grooved pulley 15is supplied to the takeup station, where it is wound up on theassociated takeup reel 21 Each takeup reel 21 is driven with a forwardslip by a separate variable-tension motor 22, by means of which thetension of the wire D being wound up can be adjusted. The requiredtension of the wire and a snug contact of the same with the groovedpulley is ensured by this winding tension in combination with theopposing tension, which is either produced directly by the wire supplyreel 1 or by an adjustable snubber 4, which engages the wire before itsfirst contact with the grooved pulley 15. The oven body 10 also carriesa device for threading the wires. This threading device consists of anendless belt 19, which extends through both drying retorts 10a and 10band cooperates with guide pulleys 18, which are slidable throughout thewidth of the oven from one wire-handling line to the other on an axle.on which they are rotatably mounted. Two of said axles are disposed onrespective sides of the oven body 10.

In such oven installations for use in the manufacture of enameled wire,the arrangement may be such that the enamel coating vessels 11a and 11b,which precede the oven body 10 in the direction of movement of each wirepass, are divided into compartments, each of which is associated withone wire D so that difierent kinds of enamel may be applied to differentwires. In this case, the several compartments of the enamel coatingvessels 11a and 11b preceding the oven body 10 may be separatelysupplied with enamel in a controlled manner; this supply may beautomatically controlled in dependence on the desired thickness of theenamel coat. Because the supply of enamel IS separately metered, e.g.,by means of a metering pump, it is sufficient in this arrangement tosupply enamel at the rate which is required to obtain a coat having apredetermined thickness. This metering pump associated with each wire Dmay be automatically controlled in dependence on the wire diameter sothat a selected thickness of coat may be maintained most accurately Theoven installation according to the invention for the manufacture ofenameled wire is not restricted to the embodiments which are describedand shown here but different structural changes in the oven installationmay be effected to meet special requirements. Above all, instead ofwires to be coated with insulating enamel, other elongated elements orprofiled rods may be coated with enamel or other varnishes or paints orwith other liquid to viscous binders.

For use in the manufacture of wires having two enamel coats, the oveninstallation according to the invention may comprise, e.g., four dryingretorts, which are superimposed and accommodated in a common oven body10 and together with the associated guiding and reversing elements 15-13form two identical multiple-line enamel coating systems. In this case,several wires D may first be moved through the two upper retorts and maythen be reversed by the respective individual pulleys l3 and 15 afterthey have been coated with enamel in the respective enamel coatingvessels 1 1 and may be repeatedly moved in opposite directions until anenamel primer coat in the desired thickness has been obtained. This wirehaving a primer coat is then deflected to the lower one of twoassociated sectional grooved rolls l5 and is repeatedly moved throughthe two other, lower retorts until an enamel cover coat in the desiredthickness has been formed. in this arrangement, each of the twosuperimposed grooved r0115 disposed on one side of the oven 10 comprisesa plurality of sections, each of which is associated with one wire, andthe roll sections associated with a given wire are synchronously drivenby a common control unit and independently of the other roll sections.This control unit thus determines the speed of travel. Higher speeds maybe obtained if drying passes are provided between enamel coating passesin known manner.

What I claim is:

1. An oven installation for use in the manufacture of enameled wires,which comprises an oven body,

first and second drying retorts provided in said oven body,

first and second enamel coating means,

a plurality of wire-handling lines, each of which is operable to move awire to be enameled in a first direction along a first pass path throughsaid first enamel coating means and thereafter through said first dryingretort in a first plane, then to move said said wire in a seconddirection, which is opposite to the first, along a second pass paththrough said second enamel coating means and thereafter through saidsecond drying retort in a second plane, which is parallel to said firstplane, and to repeat said movement of said wire in said first directionthrough said first enamel coating means and through said first retort insaid first direction in said first plane along at least one additionalodd-numbered pass path and through said second coating means and saidsecond retort in said second direction in said second plane along atleast one additional even-numbered pass path,

said first and second planes being common to all said wirehandlinglines,

each of said wire-handling lines comprising first reversing means forguiding said wire from each odd-numbered pass path to the nextsucceeding even-numbered pass path, and second reversing means forguiding said wire from each but the last even-numbered pass path to thenext succeeding odd-numbered pass path,

said first reversing means comprising first axle means extending in saidfirst plane, a first set of pulleys freely rotatably mountedindependently of each other on said first axle means, second axle meansextending in said second plane, and a second set of pulleys freelyrotatably mounted independently of each other on said second axle means,

said second reversing means of each of said wire-handling linescomprising a single multigrooved pulley,

each of said wire-handling lines comprising a variable-speed drive unitand an endless tensile element operatively connecting said drive unit tosaid multigrooved pulley to drive the same, whereby said multigroovedpulle'y is operable to pull said wire through said drying retorts,

said installation comprising a common axle, on which all saidmultigrooved pulleys are rotatably mounted, and

threading means comprising an endless belt extending through said ovenand transversely sliiftable seriatim to each of said plurality ofwire-handling lines.

2. An oven installation as set forth in claim 1, in which said driveunit is a variable-speed electric motor.

3. An oven installation as set forth in claim 1, in which said endlesstensile element is a V-belt.

4. An oven installation as set forth in claim 1, in which said driveunits are disposed between said oven body, said multigrooved pulleys,and said first and second planes.

5. An oven installation as set forth in claim 1, which comprises atakeup station comprising a plurality of reels, each of which is adaptedto receive said wire from one of said multigrooved pulleys,

said takeup station further comprising a plurality of takeup motors,each of which is operatively connected to one of said reels and operableto maintain a predetermined adjustable tension in the wire moving fromsaid multigrooved pulley to said reel, and

control means arranged to control the speed of each of said takeupmotors in dependence on the speed of the associated multigrooved pulley.

6. An oven installation as set forth in claim 5, in which each of saidtakeup motor is a direct current electric motor having a hyperbolictorque-speed characteristic.

7. An oven installation as set forth in claim 1, in which each of saidmultigrooved pulleys has a final delivery groove, which is aligned withsaid last even-numbered pass path, and

each of said wire-handling lines comprises a pressure roller whichcontacts said multigrooved pulley at said final delivery groove to holdsaid wire in frictional driving contact with said multigrooved pulley.

8. An oven installation as set forth in claim 1, in which each of saidwire-handling lines comprises an automatic stop motion arranged tointerrupt the operation of said wire-handling line in response to apredetermined change in operating conditions.

9. An oven installation as set forth in claim 8, in which said stopmotion is responsive to the breakage of the wire handled by saidwire-handling line.

10. An oven installation as set forth in claim 1, in which said ovenbody comprises third and fourth drying retorts,

and

said first, second, third and fourth drying retorts are arranged oneover the other, and which comprises third and fourth enamel coatingmeans and a plurality of additional wire-handling lines, each of whichis operable to move a wire to be enameled in said first direction alonga third pass path through said third enamel coating means and thereafterthrough said third drying retort in a third plane, then to move saidwire in said second direction through said fourth enamel coating meansand thereafter through said fourth drying retort in a fourth plane, andto repeat said movement of said wire in said first direction throughsaid third enamel coating means and'through said third retort in saidfirst direction in said third plane along at least one additionalodd-numbered pass path and through said fourth coating means and saidfourth retort in said second direction along at least one additionaleven-numbered pass path,

said third and fourth planes being parallel to said first and secondplanes and common to all said additional wirehandling lines,

each of said additional wire-handling lines comprising third reversingmeans for guiding said wire from each oddnumbered pass path in saidthird plane to the next succeeding even-numbered pass path insaid fourthplane, and second reversing means for guiding said wire from each butthe last even-numbered pass path in said fourth plane to the nextsucceeding odd-numbered pass path in said third plane,

said third reversing means comprising third axle means extending in saidthird plane, a third set of loose pulleys freely rotatably mountedindependently of each other on said third axle means, fourth axle meansextending in said fourth plane, and a fourth set of pulleys freelyrotatably mounted independently of each other on said fourth axle means,

said fourth reversing means of each of said additional wirehandlinglines comprising a single multigrooved pulley,

each of said additional wire-handling lines comprising a variable-speeddrive unit andan endless tensile element operatively connecting saiddrive unit to said multigrooved pulley to drive the same, whereby saidmultigrooved pulley of each of said additional wire-handling lines isoperable to pull said wire through said third and fourth drying retorts,

said installation comprising an additional common axle. on handlinglines being adapted to receive said wire when it which all saidmultigrooved pulleys of said additional has moved along the last of saideven-numbered pass wire-handling lines are rotatably mounted. and pathsin said second plane.

said multigrooved pulley of each of said additional wire-

1. An oven installation for use in the manufacture of enameled wires, which comprises an oven body, first and second drying retorts provided in said oven body, first and second enamel coating means, a plurality of wire-handling lines, each of which is operable to move a wire to be enameled in a first direction along a first pass path through said first enamel coating means and thereafter through said first drying retort in a first plane, then to move said said wire in a second direction, which is opposite to the first, along a second pass path through said second enamel coating means and thereafter through said second drying retort in a second plane, which is parallel to said first plane, and to repeat said movement of said wire in said first direction through said first enamel coating means and through said first retort in said first direction in said first plane along at least one additional odd-numbered pass path and through said second coating means and said second retort in said second direction in said second plane along at least one additional even-numbered pass path, said first and second planes being common to all said wirehandling lines, each of said wire-handling lines comprising first reversing means for guiding said wire from each odd-numbered pass path to the next succeeding even-numbered pass path, and second reversing means for guiding said wire from each but the last even-numbered pass path to the next succeeding odd-numbered pass path, said first reversing means comprising first axle means extending in said first plane, a first set of pulleys freely rotatably mounted independently of each other on said first axle means, second axle means extending in said second plane, and a second set of pulleys freely rotatably mounted independently of each other on said second axle means, said second reversing means of each of said wire-handling lines comprising a single multigrooved pulley, each of said wire-handling lines comprising a variable-speed drive unit and an endless tensile element operatively connecting said drive unit to said multigrooved pulley to drive the same, whereby said multigrooved pulley is operable to pull said wire through said drying retorts, said installation comprising a common axle, on which all said multigrooved pulleys are rotatably mounted, and threading means comprising an endless belt extending through said oven and transversely shiftable seriatim to each of said plurality of wire-handling lines.
 2. An oven installation as set forth in claim 1, in which said drive unit is a variable-speed electric motor.
 3. An oven installation as set forth in claim 1, in which said endless tensile element is a V-belt.
 4. An oven installation as set forth in claim 1, in which said drive units are disposed between said oven body, said multigrooved pulleys, and said first and second planes.
 5. An oven installation as set forth in claim 1, which comprises a takeup station comprising a plurality of reels, each of which is adapted to receive said wire from one of said multigrooved pulleys, said takeup station further comprising a plurality of takeup motors, each of which is operatively connected to one of said reels and operable to maintain a predetermined adjustable tension in the wire moving from said multigrooved pulley to said reel, and control means arranged to control the speed of each of said takeup motors in dependence on the speed of the associated multigrooved pulley.
 6. An oven installation as set forth in claim 5, in which each of said takeup motor is a direct current electric motor having a hyperbolic torque-speed characteristic.
 7. An oven installation as set forth in claim 1, in which each of said multigrooved pulleys has a final delivery groove, which is aligned with said last even-numbered pass path, and each of said wire-handling lines comprises a pressure roller which contacts said multigrooved pulley at said final delivery groove to hold said wire in frictional driving contact with said multigrooved pulley.
 8. An oven installation as set forth in claim 1, in which each of said wire-handling lines comprises an automatic stop motion arranged to interrupt the operation of said wire-handling line in response to a predetermined change in operating conditions.
 9. An oven installation as set forth in claim 8, in which said stop motion is responsive to the breakage of the wire handled by said wire-handling line.
 10. An oven installation as set forth in claim 1, in which said oven body comprises third and fourth drying retorts, and said first, second, third and fourth drying retorts are arranged one over the other, and which comprises third and fourth enamel coating means and a plurality of additional wire-handling lines, each of which is operable to move a wire to be enameled in said first direction along a third pass path through said third enamel coating means and thereafter through said third drying retort in a third plane, then to move said wire in said second direction through said fourth enamel coating means and thereafter through said fourth drying retort in a fourth plane, and to repeat said movement of said wire in said first direction through said third enamel coating means and through said third retort in said first direction in said third plane along at least one additional odd-numbered pass path and through said fourth coating means and said fourth retort in said second direction along at least one additional even-numbered pass path, said third and fourth planes being parallel to said first and second planes and common to all said additional wire-handling lines, each of said additional wire-handling lines comprising third reversing means for guiding said wire from each odd-numbered pass path in said third plane to the next succeeding even-numbered pass path in said fourth plane, and second reversing means for guiding said wire from each but the last even-numbered pass path in said fourth plane to the next succeeding odd-numbered pass path in said third plane, said third reversing means comprising third axle means extending in said third plane, a third set of loose pulleys freely rotatably mounted independently of each other on said third axle means, fourth axle means extending in said fourth plane, and a fourth set of pulleys freely rotatably mounted independently of each other on said fourth axle means, said fourth reversing means of each of said additional wire-handling lines comprising a single multigrooved pulley, each of said additional wire-handling lines comprising a variable-speed drive unit and an endless tensile element operatively connecting said drive unit to said multigrooved pulley to drive the same, whereby said multigrooved pulley of each of said additional wire-handling lines is operable to pull said wire through said third and fourth drying retorts, said installation comprising an additional common axle, on which all said multigrooved pulleys of said additional wire-handling lines are rotatably mounted, and said multigrooved pulley of each of said additional wire-handling lines being adapted to receive said wire when it has moved along the last of said even-numbered pass paths in said second plane. 